// tutorial03.c
// A pedagogical video player that will stream through every video frame as fast as it can
// and play audio (out of sync).
//
// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard, 
// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
// Use
//
// gcc -o tutorial03 tutorial03.c -lavformat -lavcodec -lz -lm `sdl-config --cflags --libs`
// to build (assuming libavformat and libavcodec are correctly installed, 
// and assuming you have sdl-config. Please refer to SDL docs for your installation.)
//
// Run using
// tutorial03 myvideofile.mpg
//
// to play the stream on your screen.


#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h> 

#include <SDL/SDL.h>
#include <SDL/SDL_thread.h>
#include <assert.h>

#ifdef __MINGW32__
#undef main /* Prevents SDL from overriding main() */
#endif

#include <stdio.h>

#define SDL_AUDIO_BUFFER_SIZE 1024

int img_convert(AVPicture *dst, int dst_pix_fmt,  
                const AVPicture *src, int src_pix_fmt,  
                int src_width, int src_height)  
{  
    int w;  
    int h;  
    static struct SwsContext *pSwsCtx;  

  
    w = src_width;  
    h = src_height;  
    pSwsCtx = sws_getContext(w, h, src_pix_fmt,  
                            w, h, dst_pix_fmt,  
                            SWS_BICUBIC, NULL, NULL, NULL);  
  
    sws_scale(pSwsCtx, (const uint8_t* const*)src->data, src->linesize,  
            0, h, dst->data, dst->linesize);  
 
 
    return 0;  
} 


typedef struct PacketQueue 
{
	AVPacketList *first_pkt, *last_pkt;
	int nb_packets;
	int size;
	SDL_mutex *mutex;
	SDL_cond *cond;
} PacketQueue;

PacketQueue audioq;

int quit = 0;

void packet_queue_init(PacketQueue *q) 
{
	memset(q, 0, sizeof(PacketQueue));
	q->mutex = SDL_CreateMutex();
	q->cond = SDL_CreateCond();
}

int packet_queue_put(PacketQueue *q, AVPacket *pkt) 
{
	AVPacketList *pkt1;
	if(av_dup_packet(pkt) < 0) 
	{
		return -1;
	}
	pkt1 = av_malloc(sizeof(AVPacketList));
	if (!pkt1)
		return -1;
	pkt1->pkt = *pkt;
	pkt1->next = NULL;

	SDL_LockMutex(q->mutex);

	if (!q->last_pkt)
		q->first_pkt = pkt1;
	else
		q->last_pkt->next = pkt1;
	
	q->last_pkt = pkt1;
	q->nb_packets++;
	q->size += pkt1->pkt.size;
	SDL_CondSignal(q->cond);
	SDL_UnlockMutex(q->mutex);
	return 0;
}

static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
{
	AVPacketList *pkt1;
	int ret;

	SDL_LockMutex(q->mutex);
	for(;;)
	{
		if(quit) 
		{
			ret = -1;
			break;
		}

		pkt1 = q->first_pkt;
		if (pkt1) 
		{
			q->first_pkt = pkt1->next;
			if (!q->first_pkt)
			q->last_pkt = NULL;
			q->nb_packets--;
			q->size -= pkt1->pkt.size;
			*pkt = pkt1->pkt;
			av_free(pkt1);
			ret = 1;
			break;
		}
		else if (!block)
		{
			ret = 0;
			break;
		}
		else
		{
			SDL_CondWait(q->cond, q->mutex);
		}
	}
	SDL_UnlockMutex(q->mutex);
	return ret;
}

int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size) 
{
	static AVPacket pkt;
	static AVPacket pkt_temp;

	int len1, data_size;

	for(;;) 
	{
		while(pkt_temp.size > 0)
		{
			data_size = buf_size;
			len1 = avcodec_decode_audio3(aCodecCtx, (int16_t *)audio_buf, &data_size, &pkt_temp);
	
			if(len1 < 0)
			{
				/* if error, skip frame */
				pkt_temp.size = 0;
				break;
			}
			pkt_temp.data += len1;
			pkt_temp.size -= len1;
	
			if(data_size <= 0)
			{
				/* No data yet, get more frames */
				continue;
			}
			/* We have data, return it and come back for more later */
			return data_size;
		}
		if(pkt.data)
			av_free_packet(&pkt);
		memset(&pkt_temp, 0, sizeof(pkt_temp));

		if(quit)
		{
			return -1;
		}

		if(packet_queue_get(&audioq, &pkt, 1) < 0) {
			return -1;
		}
		pkt_temp = pkt;
		
	}
}

void audio_callback(void *userdata, Uint8 *stream, int len)
{

	AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
	int len1, audio_size;

	static uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];
	static unsigned int audio_buf_size = 0;
	static unsigned int audio_buf_index = 0;

	while(len > 0) 
	{
		if(audio_buf_index >= audio_buf_size) 
		{
			/* We have already sent all our data; get more */
			audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));
			if(audio_size < 0)
			{
				/* If error, output silence */
				audio_buf_size = 1024; // arbitrary?
				memset(audio_buf, 0, audio_buf_size);
			}
			else
			{
				audio_buf_size = audio_size;
			}
			audio_buf_index = 0;
		}
		len1 = audio_buf_size - audio_buf_index;
		if(len1 > len)
			len1 = len;
		memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
		len -= len1;
		stream += len1;
		audio_buf_index += len1;
	}
}

int main(int argc, char *argv[])
{
	AVFormatContext *pFormatCtx;
	int             i, videoStream, audioStream;
	AVCodecContext  *pCodecCtx;
	AVCodec         *pCodec;
	AVFrame         *pFrame; 
	AVPacket        packet;
	int             frameFinished;
	float           aspect_ratio;

	AVCodecContext  *aCodecCtx;
	AVCodec         *aCodec;

	SDL_Overlay     *bmp;
	SDL_Surface     *screen;
	SDL_Rect        rect;
	SDL_Event       event;
	SDL_AudioSpec   wanted_spec, spec;

	if(argc < 2)
	{
		fprintf(stderr, "Usage: test <file>\n");
		exit(1);
	}
	// Register all formats and codecs
	av_register_all();

	if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER))
	{
		fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
		exit(1);
	}

	// Open video file
	pFormatCtx = avformat_alloc_context();
	if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
		return -1; // Couldn't open file

	// Retrieve stream information
	if(av_find_stream_info(pFormatCtx)<0)
		return -1; // Couldn't find stream information

	// Dump information about file onto standard error
	av_dump_format(pFormatCtx, 0, argv[1], 0);

	// Find the first video stream
	videoStream=-1;
	audioStream=-1;
	for(i=0; i<pFormatCtx->nb_streams; i++)
	{
		if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO && videoStream < 0)
		{
			videoStream=i;
		}
		if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO && audioStream < 0) 
		{
		 	audioStream=i;
		}
	}
	if(videoStream==-1)
		return -1; // Didn't find a video stream
	if(audioStream==-1)
		return -1;

	aCodecCtx=pFormatCtx->streams[audioStream]->codec;
	// Set audio settings from codec info
	wanted_spec.freq = aCodecCtx->sample_rate;
	wanted_spec.format = AUDIO_S16SYS;
	wanted_spec.channels = aCodecCtx->channels;
	wanted_spec.silence = 0;
	wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
	wanted_spec.callback = audio_callback;
	wanted_spec.userdata = aCodecCtx;

	if(SDL_OpenAudio(&wanted_spec, &spec) < 0)
	{
		fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
		return -1;
	}
	aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
	if(!aCodec)
	{
		fprintf(stderr, "Unsupported codec!\n");
		return -1;
	}
	avcodec_open(aCodecCtx, aCodec);

	// audio_st = pFormatCtx->streams[index]
	packet_queue_init(&audioq);
	SDL_PauseAudio(0);

	// Get a pointer to the codec context for the video stream
	pCodecCtx=pFormatCtx->streams[videoStream]->codec;

	// Find the decoder for the video stream
	pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
	if(pCodec==NULL)
	{
		fprintf(stderr, "Unsupported codec!\n");
		return -1; // Codec not found
	}
	// Open codec
	if(avcodec_open(pCodecCtx, pCodec)<0)
		return -1; // Could not open codec

	// Allocate video frame
	pFrame=avcodec_alloc_frame();

	// Make a screen to put our video

#ifndef __DARWIN__
	    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
#else
	    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
#endif
	if(!screen)
	{
		fprintf(stderr, "SDL: could not set video mode - exiting\n");
		exit(1);
	}

	// Allocate a place to put our YUV image on that screen
	bmp = SDL_CreateYUVOverlay(pCodecCtx->width,
				 pCodecCtx->height,
				 SDL_YV12_OVERLAY,
				 screen);


	// Read frames and save first five frames to disk
	i=0;
	while(av_read_frame(pFormatCtx, &packet)>=0) 
	{
		// Is this a packet from the video stream?
		if(packet.stream_index==videoStream) 
		{
			// Decode video frame
			avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished,&packet);
			  
			// Did we get a video frame?
			if(frameFinished) 
			{
				SDL_LockYUVOverlay(bmp);

				AVPicture pict;
				pict.data[0] = bmp->pixels[0];
				pict.data[1] = bmp->pixels[2];
				pict.data[2] = bmp->pixels[1];

				pict.linesize[0] = bmp->pitches[0];
				pict.linesize[1] = bmp->pitches[2];
				pict.linesize[2] = bmp->pitches[1];

				// Convert the image into YUV format that SDL uses
				img_convert(&pict, PIX_FMT_YUV420P,
				                (AVPicture *)pFrame, pCodecCtx->pix_fmt, 
					    pCodecCtx->width, pCodecCtx->height);

				SDL_UnlockYUVOverlay(bmp);

				rect.x = 0;
				rect.y = 0;
				rect.w = pCodecCtx->width;
				rect.h = pCodecCtx->height;
				SDL_DisplayYUVOverlay(bmp, &rect);
				av_free_packet(&packet);
			}
		} 
		else if(packet.stream_index==audioStream)
		{
			packet_queue_put(&audioq, &packet);
		}
		else
		{
			av_free_packet(&packet);
		}
		// Free the packet that was allocated by av_read_frame
		SDL_PollEvent(&event);
		switch(event.type)
		{
			case SDL_QUIT:
				quit = 1;
				SDL_Quit();
				exit(0);
				break;
			default:
				break;
		}

	}

	// Free the YUV frame
	av_free(pFrame);

	// Close the codec
	avcodec_close(pCodecCtx);

	// Close the video file
	av_close_input_file(pFormatCtx);

	return 0;
}
